Unit 2 - Ecosystems & Ecology

Species

A group of organisms that can interbreed and produce fertile offspring

Population

A group of individuals of the same species living in a specific area

Community

Different populations living and interacting in the same area

Ecosystem

A community and its abiotic environment

Habitat

The environment where a species normally lives

Niche

The role of an organism within its ecosystem, including its interactions and resource use

Biotic factors

Living components of an ecosystem (e.g. plants, animals, bacteria)

Abiotic factors

Non-living components of an ecosystem (e.g. temperature, water, sunlight)

Trophic level

A step in the food chain (e.g. producers, primary consumers, secondary consumers)

Food chain

A linear sequence showing energy flow through an ecosystem

Food web

A network of interconnected food chains

Bioaccumulation

The buildup of toxins in an individual organism

Biomagnification

The increasing concentration of toxins as they move up the food chain

Carrying capacity

The maximum population size an environment can support sustainably

Fundamental niche

The full range of conditions and resources a species could theoretically use without competition

Realized niche

The actual conditions and resources a species could theoretically use without competition

Intraspecific competition

Competition between members of the same species

Interspecific competition

Competition between different species

Parasitism

A symbiotic relationship where one organism benefits while the other is harmed

Mutualism

A symbiotic relationship where both species benefit

Pyramid of biomass

A diagram that represents the total dry mass of organisms at each trophic level

Pyramid of numbers

A diagram showing the number of individuals at each trophic level

Pyramid of productivity

A diagram that shows the flow of energy through each trophic level over time

Gross primary productivity

The total energy fixed by plants through photosynthesis

Net primary productivity

The energy remaining after plants use some for respiration

Gross secondary productivity

The total energy ingested by consumers minus energy lost in feces

Net secondary productivity

The energy left after consumers use some for respiration

Carbon cycle

The movement of carbon through photosynthesis, respiration, combustion, and decomposition

Nitrogen cycle

The movement of nitrogen through nitrogen fixation, nitrification, and denitrification

Water cycle

The continuous movement of water through evaporation, condensation, precipitation, and infiltration

Biome

A large geographical area with similar climate, vegetation, and wildlife

Zonation

The change in ecosystem structure along an environmental gradient (e.g. latitude)

Succession

The natural process of change in species composition in an ecosystem over time

Primary succession

Succession that starts on bare rock of a newly formed surface

Secondary succession

Succession that occurs in an area that previously supported life but was disturbed

Climax community

The stable and mature stage of ecological succession

Pioneer species

The first species to colonize an area in primary succession (e.g. lichens, mosses)

K-strategists

Species that produce few offspring with high parental investment

R-strategists

Species that produce many offspring with little to no parental care

Mark-recapture method

A technique used to estimate animal population size by capturing, marking, and recapturing individuals

Simpson’s diversity index

A mathematical measure of biodiversity that considers species richness and evenness

Species richness

Number of different species in an area

Species evenness

Relative abundance of each species in an area

R-strategists

Species that produce many offspring, invest little parental care, and thrive in unstable or unpredictable environments (e.g. insects, bacteria, weeds)

K-strategists

Species that produce fewer offspring, invest heavily in parental care and thrive in stable environments near carrying capacity (e.g. elephants, humans, whales)